Abstract
In this study, we have explored the transcriptomic response of Streptococcus pneumoniae D39 to N-acetylglucosamine (NAG). Transcriptome comparison of S. pneumoniae D39 wild-type grown in chemically defined medium (CDM) in the presence of 0.5% NAG to that grown in the presence of 0.5% glucose revealed elevated expression of many genes/operons, including nagA, nagB, manLMN, and nanP. We have further confirmed the NAG-dependent expression of nagA, nagB, manLMN, and nanP by β-galactosidase assays. nagA, nagB and glmS are putatively regulated by a transcriptional regulator NagR. We predicted the operator site of NagR (dre site) in PnagA, PnagB, and PglmS, which was further confirmed by mutating the predicted dre site in the respective promoters (nagA, nagB, and glmS). Growth comparison of ΔnagA, ΔnagB, and ΔglmS with the D39 wild-type demonstrates that nagA and nagB are essential for S. pneumoniae D39 to grow in the presence of NAG as a sole carbon source. Furthermore, deletion of ccpA shows that CcpA has no effect on the expression of nagA, nagB, and glmS in the presence of NAG in S. pneumoniae.
Highlights
Pneumonia, sepsis, meningitis, otitis media, and conjunctivitis are a few of the diseases caused by the major human pathogen Streptococcus pneumoniae that results in over a million deaths each year worldwide (Ispahani et al, 2004; O’Brien et al, 2009)
The NAG regulon consists of nagA, nagB, and glmS in S. mutans, and is regulated by a GntR-family transcriptional regulator NagR (Moye et al, 2014)
We explored the global impact of ccpA deletion on the transcriptome of S. pneumoniae in the presence of NAG, showing that ccpA has no effect on the expression of nagA, nagB, and glmS
Summary
Sepsis, meningitis, otitis media, and conjunctivitis are a few of the diseases caused by the major human pathogen Streptococcus pneumoniae that results in over a million deaths each year worldwide (Ispahani et al, 2004; O’Brien et al, 2009). S. pneumoniae has several extracellular glycosidases with an extensive variety of substrates specificities and can make use of the other host glycans, such as N-glycans and glycosaminoglycans (Burnaugh et al, 2008; King, 2010; Marion et al, 2012). These enzymes produce a number of free sugars that potentially can be used by the pneumococcus. The role of these enzymes in in vivo fitness is demonstrated by the findings that glycosidase mutants show attenuated capacity to colonize and to cause disease in mouse models (Tong et al, 2000; Jeong et al, 2009; Marion et al, 2009; Terra et al, 2010)
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